Prior degaussers typically require manual manipulation of magnetic storage media, such as magnetic storage tape, hard disk drives, and the like, by a user in between passes of the media through a magnetic field to achieve uniform multidirectional magnetic field exposure for optimum erasure performance. The raw magnetic strength applied to certain magnetic storage media such as hard disk drives can overcome the lack of multidirectional exposure in the plane of the disk along the directions of the circular tracks recorded on the disk. Meanwhile, hard disk drive technology has advanced to the era of perpendicular recording on the disk with increasing coercivity ratings requiring a higher applied magnetic field strength for erasure.
Perpendicular recording and the possibility of further coercivity increases in magnetic disk drives are creating a demand for perpendicular magnetic field strength and an approximately equivalent horizontal magnetic field strength to be applied in degaussers. Typically, the disks are only partially constrained in the drive by the frictional force of parked heads, and strong erase fields acting on the spindle rotors might overcome that force, leading to less than certain demagnetization results.
Certain prior attempts to erase hard disk drives included apparatuses that apply a degaussing magnetic field almost directly to the disk while rotating the disk within the drive. The relationship, however, between external features of various hard disk drive brands and models and their internal components like spindle motors and head motors are not universally obvious. Therefore, in general application it is desirable to treat the entire volume of each hard disk drive.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the arts will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.